Rock drill tappet



Sept. 9, 1941. M. c. HUFFMAN Filed Dec. 16, 1940 MQ Tw mv W lull I1..

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Patented Sept. 9, 1941 ROCK DRILL TAPPET Mervin C. Huffman, Denver, Colo., assignor to Gardner-Denver Company, Quincy, Ill., a corporation of Delaware Application December 16, 1940, Serial No. 370,309

4 Claims.

This invention relates to improvements in rock drills of the hammer piston type and is more particularly directed to the means for transmitting energy from the hammer piston to the steel.

The object of the invention is to provide a striking memberbetween the hammer piston and the steel of such a structure as to insure its movement in a line parallel to the axis of the drill and steel.

Another object of the invention is to provide an intermediate member between the hammer piston and the steel of such a structure as to insure a maximum bearing for the member during its movement.

Further objects of the invention will hereinafter appear, and to all of these ends the invention consists of the features of construction, arrangement of parts, and combination of elements, substantially as hereinafter fully described and claimed in the specification and shown in the accompanying drawing, in which:

Figure l is a sectional View taken through the front part of a rock drill showing the hammer piston and the steel with an energy transmitting member therebetween.

Figure 2 is an enlarged parallel prospective of the energy transmitting member, and

Figure 3 is a sectional view taken on the line 3-3 of Figure 1.

Briefly the invention hereinabout to be described deals with the provision of an energy transmitting member between the hammer piston of a rock drill and the steel, such a member being hereinafter referred to as a tappet.

Usually in rock drills embodying a tappet considerable difficulty has been experienced in maintaining true faces upon its ends. Such a .condition is the result of several controlling factors. As an example, the steel may not be in true alignment with the axis of the hammer lpiston causing a cooking of the tappet between the two and the transmitting of energy through limited areas, frequently outside of the true axis of the tappet. Then again improper alignment may be the result of convexed or concaved faces on the ends of the steel used. When such conditions exist the blow transmitted to the tappet by the hammer is more of a glancing or off-side blow than a direct one and continued operation under such improper conditions aggravates the failure in the tappet, causing its complete break down with possibly a few hours of use. Frequently this failure results in destroying the bearing within which the tappet reciprocates.

Ordinarily the tappet of a rock drill is a cylindrical block of steel having an enlarged head and a reduced shank portion and it frequently occurs that its enlarged head or extending flange breaks or chips olf from the shank. Such a failure is primarily due to the lack of suflicient bearing when the impact of the tappet with the steel occurs.

It is the object of the present invention to provide a tappet wherein it is fully supported during its reciprocations. Upon referring to the drawing, it will be observed that the tappet is in reality a cylindrical block of steel from end to end and has formed upon its periphery, ribs extending from one end and continuing to a point near the other end of the tappet or to a distance approaching the desired length of the tappet head.

With such a structure, it is quite apparent that the full diameter of the tappet head which extends from one end to the other serves to support the tappet throughout its entire length during its movement and as a result misalignment of the tappet between the hammer piston and the steel is eliminated.

Referring to the drawing in detail, particularly to Figure 1 wherein a section of a rock drill is disclosed, the numeral l indicates a portion of a rock drill cylinder having secured to its front end a chuck housing 2 of any conventional design.

Positioned within the cylinder l is the usual reciprocating hammer piston 3 being controlled in its movements by a fluid distributing valve, not disclosed. As illustrated in Figure l, the hammer piston 3 has a reduced shank 4 the major portion of which is provided with longitudinal flutes 5 and these engage corresponding flutes formed in a nut 6 removably positioned within the rear end of a rotating sleeve 1; the sleeve 'I being receivable within the housing 2.

The front end of the sleeve 'I is suitably interlocked with a steel receiving bushing 3 having a peripheral ange 9, positioned between the inner front end of the housing 2 and the front face of the sleeve l.

The bushing 8 is provided with a suitable bore of any desired shape receiving therein the shank end of a steel l0, which in this particular instance is hexagonal.

The foregoing structure is common in the present day practice and it is apparent that rotation of the steel by the hammer is permitted.

The central portion of the sleeve 'l has formed integral therewith an inwardly extending ange ll, the front face of which is provided with a desired radius, equal to that formed on the energy transmitting member or tappet. The internal periphery of the flange has a plurality of longitudinal flutes I2, extending parallel with the aXis of the sleeve. Positioned within a chamber I3 formed within the sleeve I and between the rear end of the bushing 8 and the flange I I is a reciprocating tappet I4, more clearly disclosed in Figure 2. The tappet I4 is adapted to have one end struck by the end face formed on the shank of the hammer 3, transmitting blows therefrom to the steel.

As disclosed in Figure 2, the tappet I 4 is formed of a cylindrical member having longitudinal and parallel flutes I 5 extending approximately its full length or to a point permitting the formation of the usual cylindrical head. The purpose of the latter being to guide the tappet and maintain the same in alignment during its movement.

As disclosed in Figures l and 3, the flutes I5 of the tappet are adapted to interlock with the utes I2 formed in the bearing I I, but permitting proper longitudinal movement of the tappet within the bearing.

From this structure it is clearly appar-ent that when the hammer piston moves forward to strike the rear face of the tappet, movement of the tappet in a straight line within its bearing II is permitted, due to the interlocking relation between the bearing I I and the tappet itself trans mitting the blow to the steel. Correct alignment of the tappet with the hammer and steel is thus maintained during its entire movement.

With such a structure the bearing surface of the usual tappet is increased in area and a tappet more correctly balanced is presented. It is obvious that with this structure the overbalancing and tipping of the tappet, should the latter become worn, is eliminated.

From the foregoing it is thought that the construction, operation and many advantages of the herein described invention will be apparent to those skilled in the art without further description, and it will be understood that various changes in the size, shape, proportion and minor details of construction may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

What I claim is:

1. In a rock drill, the combination of a cylinder having therein a reciprocating hammer piston, a chuck secured to the cylinder and receiving therein a steel, a tappet between the piston and steel transmitting blows from the former to the latter, a guide element for the tappet, and said tappet and element having co-acting ribs forming a support for the tappet during its movement.

2. In a rock drill, the combination of a cylinder having therein a reciprocating hammer piston, a chuck secured to the cylinder and receiving therein a steel, a tappet between the piston and steel transmitting blows from the former to the latter, said tappet having an enlarged head engageable with the steel and a shank receiving the blows from the piston, a guide element for the tappet, and said shank portion Aof the tappet and the element having co-acting ribs serving to support the tappet during its movement.

3. In a rock drill, the combination of a. cylinder having therein a reciprocating hammer piston, a chuck secured to the cylinder and receiving therein a steel, a tappet between the piston and steel transmitting blows from the former to the latter, a guide element for the tappet, and said tappet and element having co-acting surfaces serving to increase the bearing area of the tappet during its movement.

4, In a rock drill, the combination of a cylinder having therein a reciprocating hammer piston, a chuck secured to the cylinder and receiving therein a steel, a tappet between the piston and steel transmitting blows from the former to the latter, a guide element for the tappet, and said tappet and element having bearing faces of increased areas upon their peripheries serving to maintain the tappet in true alignment with the hammer and steel during its movement.

MERVIN C. HUFFNIAN. 

